Conventionally, when an operator conducts telephone communications with a customer in a call center, in order to support an appropriate response to the customer, a technology is known of measuring a psychological state of the customer from the customer's utterances during the communications and reporting the psychological state of the customer to the operator. As examples of technologies of grasping the psychological state of a customer, a technology of determining a dissatisfaction level of the customer by the number of dissatisfaction keywords expressed during communications, or a technology of obtaining utterance information of the customer by utterance recognition processing and determining the customer's emotions by using rhythmic features such as verbal information, speech speed, utterance volume, and the like, is known. Further, a technology of determining a user's emotions by relating words to emotions is also known. However, since the customer often does not express his real emotions, trying to control his emotions during the conversations with the operator, it is difficult to accurately grasp the psychological state of the customer by utterances during the communications by conventional technologies. Therefore, in order to accurately measure the psychological state of the customer, a technology of obtaining the utterances of the customer without the conscious knowledge of the operator and measuring the psychological state of the customer by utilizing the obtained utterances is desired.
As related technologies, a technology of a hold release of a private branch exchange in which a held party side (customer side) may release the hold by an utterance so as to leave a message, or a technology of restoring the held party side (operator side) to a non-holding state via a request from the held party side during a holding state and calling a holding party side is known. In addition, a technology in which the held party cuts off the communications and leaves a message for the holding party, or a technology of channeling the utterances of the held party side to a monitor speaker after a lapse of a prescribed time of the holding state is known. A purpose of any of the above mentioned technology related to the holding release is that the held party side intentionally tells his request or desire to the holding party side.    Japanese Laid-open Patent Publication No. 2005-142897    Japanese Laid-open Patent Publication No. 2008-53826    Japanese Patent No. 3857922    Japanese Laid-open Patent Publication No. 2000-83098    Japanese Laid-open Patent Publication No. 06-37895    Japanese Laid-open Patent Publication No. 09-200340    Japanese Laid-open Patent Publication No. 05-219159